[TenTec] EV638 update for Orion

[Jim Brown]

There is no good reason to use a transformer with a pro dynamic mic with 
a ham rig.  In an XLR, pin 1 is the shield, pin 2 is mic +, pin 3 is mic 
return. To connect it to a ham rig, connect pin 2 (mic+) to the mic+ pin 
on the radio, tie pin 3 (mic return) and pin 1 (shield) together and 
connect them to the chassis.

An alternate wiring that also works fine -- mic+ to mic+, mic return to 
mic return, and shield to the chassis.

73, Jim K9YC

On Sat,8/16/2014 10:47 AM, K8JHR wrote:
> A few random ideas ...
>
> I would try to find a data sheet on the microphone that should 
> indicate what the transformer does and how it is wired.   I would also 
> scour the internet and look for an inexpensive dynamic microphone 
> cartridge to wire into it.  I recently "restored"  an old Shure "550"  
> Unidyne (the larger, original Elvis type microphone built in 1947) and 
> used an inexpensive dynamic mic cartridge I purchased on eBay for 
> $10.  (I can send you photos and a sound sample if you like.)  It 
> turned out swell, but I would be tempted to look for a little better 
> one next time.
>
> DATA SHEET --
>
> http://www.coutant.org/ev638/ev638.pdf
>
> More info on it:
>
> http://www.coutant.org/ev638/index.html
>
> THIS MODEL CAME AS HI OR LOW IMPEDANCE - WHICH THE
> CUSTOMER SPECIFIED ON ORDERING IT...  So I would
> think your idea of converting it may be a good one...
> but it may depend on the cartridge, and not the transformer,
> and other guts, I am not sure - some microphones use the
> same cartridge and use transformers and switches to
> change impedance, but others seem to use different
> mic cartridges as well, so that needs to be checked, but
> think the product data sheets suggest the inquiry is
> a good one.
>
>
> I would not try to fit the odd HEIL HC5 cartridge, myself, as I think 
> you can do better for less.   You could buy an inexpensive, maybe 
> used, Samson RS10s or something similar and cannibalize it for the 
> cartridge within.
>
> Another option is use the high impedance mic with an inexpensive mic 
> preamp that would better match the mic to the rig (it would use the 
> Line-IN input on the rear of the rig if there is one.)  I sometimes 
> use the M-Audio AudioBuddy preamp with my high impedance 1968 vintage 
> Shure PE-53 Sphere-o-Dyne microphone and the output of the preamp 
> makes it virtually indistinguishable from a more recent low impedance 
> mic.  (I can send a sound sample if you like...)
>
> Although I have not fully thought this out... it occurs to me that a 
> direct box (DI box) might be used to match it to the rig... or you 
> might use an in-line high-to-low-impedance transformer to better match 
> it to the rig.  Need to sleep on that idea...
>
> You might also find you are sitting too far back from the mic to get 
> its best audio output.  Proximity effects... where you sound more full 
> and bass-y up close, and thin and tinny far away, may be causing you 
> to reap less than its full capabilities.  Some guys use that mic as a 
> "harp mic" cupping it in their hands, with a harmonica, and so you, 
> too, may benefit from re-setting the MIC-GAIN after moving closer to 
> it, maybe speaking 3-4 inches from it, slightly off access to avoid 
> breathing into it, and maybe you will sound better.   Perhaps a number 
> of the above suggestions will improve its performance... such as close 
> talking it, and inserting an in-line impedance transformer, or running 
> it on a suitable preamp, or ... or...
>
> What is the inside diameter (ID) of the mic case that holds the 
> cartridge?
>
> Random thoughts... maybe something will get the click for you.
>
> Happy days.
>
> ---------------  K8JHR  --------------------------------
>
> On 8/15/2014 4:30 PM, Bill Ogden wrote:
>> I have an Orion 1 and an Electrovoice 638 Hi-Z microphone
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>